2. LipiView Ocular Surface Interferometer Tear Lipid Layer Thickness Measurement During the measurement of each eye, the participants place their chins on a chin rest and look at a single white light source for 30 seconds. During this period, participants are encouraged to blink freely at a comfortable rate which the assessor measures the LLT. Afterwards, the aforementioned steps will be repeated for the same eye by another assessor after a 5 minutes interval. Assessor 1 will perform the measurement at time 0 min, 10min and 20min while Assessor 2 will perform the measurement at time 5 min, 15 min, 25min.